How much soccer is too much soccer? From my perspective as a sports medicine specialist, I know when a player has played too much when various types of "overuse" injuries start appearing.

"My heels have been hurting for months."

"It started as soreness in my calf, but now my hamstrings and my lower back hurt, too."

These are unfortunately common problems in my practice, and usually signal that we are about to enter treatment that could keep the athlete off the field for many months.

I am definitely seeing more overuse injuries in my practice now than I did five years ago, and injuries that generally were not seen until an older age group are showing up in much younger players. In speaking with other sports medicine practitioners, these are not isolated incidents -- these injuries are definitely on the rise, and we would be wise to address the problem.

First, some definitions.

An "overuse injury" is one that occurs from repetitive usage, rather than a single event -- we are not talking about a broken ankle that happened after a rough tackle. For youth soccer players, some common overuse injuries would include Sever's Disease (heel pain - injury to the growth plate), Achilles tendonitis, shin splints, calf muscle strains, Osgood-Schlatter Syndrome (knee pain - injury to a growth plate in the front of the knee), hamstring or quadriceps muscle strains, and many others.

I would also include psychological issues such as "burnout" in the category of overuse injury.

Healing an overuse injury almost always requires an extended period of rest, physical therapy, sometimes bracing or casts, and occasionally surgery. No matter the injury, there will be a long time spent off the field. Each of us knows of a player who always seems to have something going wrong physically. That player may get labeled as "injury prone," but I believe it can really be a sign of an overused body.

Why do these injuries occur? From a scientific standpoint, the injuries occur because tissue gets repetitively loaded over time beyond the point at which it is healthy, and tissue failure occurs. Muscle fatigue, unforgiving soccer cleats, hard fields all play a role. But the bigger issue is from a social standpoint -- is there something we are subjecting young athletes to in terms of lifestyle or training that leads to overuse injury?

Many theories abound but most experts point to one main causative factor: year-round training in a single sport. What we are talking about here is structured, organized training.

I cannot recall seeing these injuries in kids playing pickup soccer, hanging out at the park, or even playing several "seasonal" sports.

Soccer's booming popularity among young athletes in the United States, combined with the potential for college scholarships and possible professional careers creates for some athletes an intense hyper-competitive environment where "success" needs to come at earlier and earlier ages. This problem is certainly not isolated to soccer, as pointed out in an excellent book, "Revolution in the Bleachers," by Regan McMahon:

Players will play for club teams (sometimes more than one club team at the same time), participate in ODP programs, and perhaps receive individual training as well. When can this body possibly heal once it has been injured?

This is a problem that has possible solutions. Competitiveness, focus, and drive are not bad things -- indeed they are admirable qualities that will serve one well through life.

But can we find for these young athletes a better balance between organized training and what in many other countries could be called "street soccer"?

The "Best Practices Guide" provides good food for thought regarding age specific recommendations for number of matches, time off, travel, and tournaments. In addition, I would submit the following for your consideration:

* Listen to your body. If you're a player with an overuse injury, understand that proper time to heal will actually shorten the amount of time you're off. If you're a coach or parent, watch for signs of overuse and address these before they lead to chronic problems. If a player is destined for a professional career, time off when they are 12 will not change that.

* Consider the U.S. Soccer Federation recommendations for age specific limits on games, travel, and tournaments, as well as recommendations for time off.

* Encourage multiple sports, at least up until age 14, and as much as possible encourage unstructured "pick up" games or free play in any sport.

With some care and attention, we can lead our kids to be better soccer players and have healthier bodies to show for it.

Dr. Mishra is an orthopedic surgeon in private practice in Burlingame and Walnut Creek, Calif. He is a team physician for U.C. Berkeley, the California Victory USL-1 club, and the U.S. Soccer Federation. Mishra's Web site is www.thesoccerdoc.com.